Pyoderma Gangrenosum

Diagnosis

Pyoderma gangrenosum (PG) is diagnosed by its characteristic appearance. Ulcer tissue is often biopsied to exclude other causes of skin ulcerations, including infection, malignancy, vasculitis, collagen vascular diseases, vascular disease and trauma. Doctors take a complete patient history with special focus on the organ systems to determine if there is underlying disease. Ulcers can be swabbed and cultured for microorganisms, but PG is not caused by an infection and is not contagious.

Autoimmune diseases are found in 50 percent of patients with PG. In 30 percent of cases, PG ulcerations may occur after trauma or injury to the skin. PG can be difficult to diagnose and multiple attempts at grafting may occur prior to its diagnosis.

PG has two main types and several other variants:

• Classic PG is marked by a deep ulceration with a purple border that overhangs the ulcer bed. Lesions usually occur on the legs, but may occur elsewhere on the body. Classic PG near a stoma (the opening surgeons make after a colostomy) is often thought to be a wound infection or irritation.
• Atypical PG has a pus- or fluid-filled component, typically at the border. It usually occurs on the back side of the hands, the forearms or the face.
• PG may occur on the genitalia (vulvar or penile PG). It is important to distinguish this variant from sexually transmitted diseases.
• An intraoral (inside the mouth) form of the disease (pyostomatitis vegetans) occurs primarily in patients with inflammatory bowel disease.
• PG is sometimes found in the lungs, liver, and bones.

Lab Tests

Tests frequently used in diagnosis of PG include:

• Routine blood tests include a complete blood count; a comprehensive chemistry profile, including a liver function test and urinalysis
• A hepatitis profile rules out hepatitis
• Serum and/or urine protein electrophoresis, peripheral smear and bone marrow aspirations are performed to evaluate for diseases of white or red blood cells
• Serum studies may include antibody and enzyme tests
• Cultures for bacteria, fungi, atypical mycobacteria and viruses

Imaging Studies

• Chest X-ray
• Colonoscopy or other tests to exclude inflammatory bowel disease or ulcerative colitis
• Angiography or Doppler echocardiography studies may be performed when arterial or venous insufficiency is suspected